Biodegradable polymers are one of the most common types of carriers used in controlled drug delivery systems. A controlled drug delivery system is normally one where the rate of drug delivery is in a predesigned mode and is delivered over extended periods, such as days, weeks or even months.
Low molecular weight polymers have been used as carriers of pharmaceutical compounds; however, they must be chemically manipulated to prevent their absorption into the bloodstream because quick absorption can cause cytotoxicity. Also, low molecular weight polymers tend to degrade quickly, thus inhibiting their ability to provide controlled delivery over a significant period of time.
High molecular weight carriers are also known. These carriers, however, tend to take a long time to degrade and be cleared from the body. The slow clearance of high molecular weight polymers can have deleterious effects on the body, such as cumulative toxicity to the kidney or liver. Also, although a polymer, per se, may not have adverse effects on an organism, the byproducts of degradation of that polymer may be toxic or have other deleterious effects on the organism.
Thus, there is a need for a readily degradable, biocompatible, high molecular weight polymer capable of controlled delivery of a pharmaceutical compound within an organism.